Adjustable rear sight for firearms



Feb. 19,1952 EMHA VEY 2,585,933

ADJUSTABLE REAR SIGHT FOR FIREARMS Filed Dec. 8, 1949 2 SHEETS-SHEET l Burl 9 l LHurvey Feb. 19, 1952 E. M. HARVEY 2,585,933

ADJUSTABLE REAR SIGHT FOR FIREARMS Filed Dec 8, 1949 2 swam-swam 2 Fig-1U- 3 we c/wto v W WM;

readily converted to a blade type sight when- I in use.

Patented Feb. 19, 1952 I UNITED STATES ADJUSTABLE REAR SIGHT FOR FIREARMS Earle M. Harvey, Agawam, Mass., assignor to the United States of America as represented by the Secretary of War Application December 8, 1949, Serial No. 131,881

7 Claims. (ol. 33- 55) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 O. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to a sight for a firearm and is particularly directed to a rear sight having means for adjustment in elevation and windage.

semiautomatic military type firearms have been improved to include means for selectively permitting full automatic fire in the event the obvious advantages of increased fire power may be required by the operator. However, insofar as is presently known, little or no attention has been paid toward the provision of an adjustable rear sight which will be equally advantageous in either full automatic or semiautomatic fire. As is well known, a peep type rear sight is commonly used for the accurate sighting required in single shot or semiautomatic fire. In full automatic fire, however, the continuous jarring and vibration of the firearm renders it almost impossible for an operator to sight accurately through a small peep hole. Increasing the size of the hole does not offer an adequate solution to this problem inasmuch as the range at which an ,25 undistorted sight picture can'be obtained is correspondingly reduced. However, it has been found that a blade type rear sight is particularly well suited for use as a battle sight at ranges up to 300 yards in either full or semiautomatic fire.

It is therefore a particular object of this invention to provide an adjustable rear sight wherein the conventional peep sight aperture can be 35 ever required without affecting the provisions; for elevation and windage adjustment.

It is another object of this invention to provide a rear sight wherein adjustments for elevation and windage can be quickly and conveniently w: effected without the existence of objectionable" backlash and wherein the adjustments, once set, will be accurately maintained despite the vibration due to continuous automatic fire.

A further object of this invention is the provision of a rear sight wherein means are provided for eliminating any horizontal and vertical play which may exist in a pivotally mounted elevation assembly as a result of clearances between the mating parts. 1

' It is still another object of this invention to provide an improved rear sight which will be relatively inexpensive to manufacture, simple in construction, and extremely durable and eflicient The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. l is a perspective view of the rear sight.

Fig. 2 is an enlarged cross-sectional elevational view of the sight.

Fig. 3 is a cross-sectional view taken along the line 3-3 in Fig. 2.

Fig. 4 is a detail view showing the aperture member of the sight engaged with the elevating post.

Fig. 5 is a cross-sectional view taken along the 'line.5-5 in Fig. 2. 1 Fig. 6 is an exploded View in perspective of the parts comprising the mechanism for adjusting the sight for windage.

Fig. 7 is a bottom view of the base member. Fig. 8 is a front view of the aperture member.

Fig.- 9 is a cross-sectional view taken along the line 99 in Fig. 8.

Fig. 10 is a side view of the elevation scale.

Fig. 11 is a front view of the elevation scale.

Fig. 12 is a detail view of the washer-like spring.

Fig. 13 is a cross-sectional view taken along the line l3- -l3 in Fig. 4. V

Fig. 14 is a fragmentary front view of the sight.

Referring more specifically to the drawings, the adjustable rear sight of this invention generally comprises a base member 5, a windage slide 6 mounted therein for transverse movement, and an elevation mechanism 1 pivotally secured to slide 6 for movement in a plane perpendicular to the transverse axis of base member 5.

A dovetailed longitudinal groove 8 is provided along the underside of base member 5 and is arranged to mate with a correspondingly dovetailed portion of a firearm receiver (not shown). Base member 5 is provided with a longitudinal split portion 9 by means of which the walls of groove 8 canto a slight extent be brought together by a 'member 5 and is counterbored to form a first annular shoulder I3 and a second annular shoulder I4 as best shown inFig. 5. The back wall of hole 12, however. is cut away along its entire length by a transverse T-slot l5 arranged to slidably receivea mating T-shaped portion 16 of windage slide 6 to which the elevation mechanism 1 is pivotally secured as by a pin la.

The rear end surface of T-shaped portion I6 is suitable curved to complete the periphery of hole l2 as well as. that of annular shoulder I4 when windage slide '6 is fully assembled in base member 5. A section of the curved rear end suriace of portion |B is provided with threads IS.

body portion 2| corresponds to threads IS on windage slide 6 and is arranged to engage therewith. A centrally located rectangular slot extends through head portion 22 and intersects the hollow interior of body portion 2|.

A cylindrical windage nut 26 is also provided With a rectangular slot 21 therethrough similar to slot 25 and arranged to be aligned therewith when assembled into hole l2 of base member 5 behind windage screw 20. One end of nut 26 is provided with a plurality of lugs 28 produced by milling diametrically intersecting slots 29 at right angles to the longitudinal axis of nut 25 as best shown in Fig. 6.

A windage knob 30 comprises a knurled cylindrical head 3| and an integral axial stem 32 having a rectangular portion 33 arranged to extend through and mate with rectangular slots 25and 21 when all the parts are assembled into counterbored hole l2 of base member '5. A coil spring 34 fits around stem 32 of knob 30 and is arranged to be compressed between knurled head 3| and the side of base member 5. A retaining pin 35 securesstem32 to windage nut 26 and thereby serves to maintain spring 34 in the compressed state. If so desired, retaining pin 35 may be staked in place in order to prevent disassembly of the windage mechanism by the soldier in the field. A screw 36extends upwardly from the bottom of base member 5 as illustrated in Fig. 5 and terminates in a cylindrical nonthreaded end portion arranged to engage between a pair of lugs 28. on windage nut '26 for a purpose to be explained.

As previously mentioned, windage slide 6 is arranged to pivotally mount the elevation mechanism 1 of the sight and is therefore provided .with ,a substantially, rectangular mounting portion 31 extending forwardly at right angles to the T-shaped portion l6 of slide E. The top forward corner of mounting portion 31 is arcuately formed. as shown at 38 in Fig. 2 and on either side .due to the existence of tolerances between T- shaped portion I6. of slide 6 and-T-s'lot [5 in base member 5. preventing possible whipping movement of elevationmechanism1 during recoil oi theflrearm As a result, the problemoi is adequately solved.

An elevation post 42 is provided with a bifurcated lower portion forming a pair of ears 44 arranged to straddle mounting portion 31 of slide 6. Ears 44 are arranged to depend from a circularfian'gfeportion 43 above which extends a substantially cylindrical upper portion 45 provided with a counterbored hole 46 extending therethrough. A pair of oppositely disposed vertical slots 41 are formed into the outer periphery of upper portion 45 and extend longitudinally therealong. A second pair of slots 1! are also provided along the outer periphery of the post upper portion similar to slots 41 but of greater vertical length as shown in Fig. 4 for a reason to be explained. The preferred embodiment as shown in the drawings utilizes two pairs of slots disposed at rightangles to one another although it is within the intent of this invention to provide for more than two pairs of slots, only one pair however being. of the. lengthof slots 1|. A coil spring 48: is arranged to fit within hole 46 with one end against an annular shoulder .49 formed by the counterbored portion of hole 46 and with the other end against a circular flange 50 on plunger 4|. Thus, the conical detent end 40 of plunger 4| is arranged to be resiliently engaged in either of V-shaped notches. 39 to maintain post 42 in either an operating, or stowed position. A screw 5| is arranged to be threadably engaged in the upper end of hole 45 for a reason to be explained. I

a A hollow sleeve 52havin'g a knurled outer periphery 53 is arranged to fit over the upper portion 45 of post 42. A pluralityof radially disposed pins 54 are slidably carried in post 42 as best shown in Fig. 3 and the outer ends. of such pins are normally arranged'to engagein an annular groove 55 provided in the interior wall of sleeve 52. A hole 56in the body of sleeve 52 is located so as toalign with each of pins 54'when sleeve 52 is rotated as will be presently described. A major portion of the interior of sleeve 52 is threaded as shown at 51 in Fig. 2 and is arranged to receive an aperture -member58.

A concavely formed washer-like spring. 59 encirclespost 42; and is retained between the bottom of sleeve 52- and thetop of flange portion 43on post 42. A pair of oppositely disposed V,- shaped detents. 6| .are formed in spring-59 and project upwardly to engage in corresponding V shaped notches 62 provided in the bottom edge of sleeve 52;. A pair. of diametrically opposed key portions H are integrally formed on spring 59 and extend inwardly; toward one another for a. purpose to be shown. 7 The space between the bottom edge of sleeve 52 and the top, of flange 43 is such that spring 59 iscompressedsufiiciently to cause detents 6| thereon to resiliently engage in notcheslil and offerresistance to the rotation of sleeve 52. v

Aperturev member 58- is exteriorly threaded at its lower end as indicated at 63in Fig. 8 and terminates in a peep portion 64 at its other end. A pair of oppositely disposed vertical keys 10 are provided in the hollow interior of aperture member 58 and are arranged to engage in either slots 41-or-1I of elevation post 42. Arectangul'ar dovetailed cut-out section 65 extending. vertically down the bodyof the aperture 58 provides for a resiliently curved substantially rectangular scale 66 having markings 51' thereon to indicate the various ranges at which the firearm sight can be set. The vertical edges o'fscale 66 are beveled so as to mate with the dovetailed walls of cutout section 65. Although the markings here shown in Figs. 8 and 11 are arranged to correspond to hundreds of yards, it should be understood that, if so desired, such markings may indicate minutes of elevation in order that ammunition of different velocities may be used without the necessity of re-zeroing the sight. A small hole 68 is punched through scale 66 adjacent the bottom portion thereof and is arranged to be engaged by any suitable tool so that scale 66 can be moved up or down as desired with respect to the body of aperture member 58.

In order to disassemble elevation mechanism I, sleeve 52 is rotated until aperture 58 is entirely disengaged therefrom. Removal of aperture 58 .from sleeve 52 exposes set screw which is then removed from post 42 permitting spring 48 and plunger 41 to be lifted out of hole 46. Next sleeve 52 is rotated until hole 56 therein is aligned with the outer end of one of pins 54. Then by means of a drift or other suitable tool, pin 54 can be pushed into post 42 sufiiciently to be withdrawn from annular groove 55. When such procedure is repeated for the remaining pins, sleeve 52 can be removed from elevation post 42. To reassemble, it is merely necessary to place sleeve 52 in the proper location over post 42, and then insert a punch or other similar tool into hole 46 and thereby force pins 54 outwardly sufficiently to extend into annular groove 55. Then the re- "stem 32 of windage knob 30 to windage nut 26,

transverse movement of knob 36 as it is pushed toward the left will cause lugs 28 to move beyond lock screw 36 in base member 5. Since the rectangular portion 33 of stem 32 engages rectangular slots and 21 of windage screw 20 and windage nut 26, these two members will also be rotated along with windage knob 30. As long as nut 26 clears lock screw 36, the rotation imparted to windage screw 20 will cause windage slide 6 to move transversely in base member 5 since threads ll! of the former engage with threads 24 of the latter. However, when manual pressure on knob is released and the spaces between lugs 28 are in alignment with lock screw 36, the bias of spring 34 will return knob 30 and consequently nut 26 to their former position. Audible clicks each indicating one quarter revolution of knob 30 are obtained when the ends of lugs 28 slip oil of lock screw 36 and spring 34 rapidly biases the mechanism so that the end portion of lugs 28 raps sharply against the head of windage screw 26. However, in the event it becomes expedient to dispense with audible clicking in order that the operator of the firearm not reveal his location to a listening enemy, sufficient pressure is maintained against knob 36 to assure that lugs 28 clear lock screw'36 and when the desired adjustment has been made, knob an is released slowly until it has fully returned to its original position. Markings 12 are provided on the top of base member 5 and an index mark 13 is formed on flange 43 of elevation post 42 for alignment with markings 72 in order to indicate the amount of windage adjustment made on either side of the zeroed position of the sight. Since the elevation post 42 is secured to the windage slide 6, transverse movement of the latter is transmitted to the former and therefore to the aperture member 56 as well. Due to the bias of spring 34 on windage knob 30, nut 26 is forced against screw 20 thereby constantly forcing the other end of windage screw 20 against shoulder M in base member 5. Consequently, any lateral movement of the windage mechanism due to the vibration and jarring of the firearm in automatic fire is rendered negligible. Moreover, backlash is virtually non-existent inasmuch as the bias of spring 34 prevents any longitudinal play between threads 24 on windage screw 20 and threads [9 on windage slide 6. As previously explained, spring 69 is effective in compensating for any clearances between T-slot l5 and T-shaped portion I6 due to tolerances in machining.

Any play between ears 44 on elevation post 42 and mounting portion 31 of windage slide 6 is prevented by the engagement of the conical end 46 of plunger 4| in the V-shaped notches 39. Since the bottoms of these notches 39 slope downwardly to the left as shown in Fig. 14 and spring 48 exerts a downward bias on plunger 4i, the conical end 40 thereof will always tend to engage in the deepest part of notches 39. Thus the right ear 44 of elevation post 42 will be constantly brought flush against the right side of slide mounting portion 31 thereby obviating any transverse play of post 42 with respect to base member 5. Vertical play is prevented through the bias of spring 48 which keeps plunger 4| firmly engaged in V-shaped notches 39.

To adjust the sight in elevation, it is merely necessary to rotate sleeve 52 clockwise or counterclockwise as desired. Since aperture member 58 is threadably engaged with sleeve 52 and is at the same time non-rotatably but slidably secured to post 42, rotation of sleeve 52 causes aperture member 59 to move vertically in a direction dependent upon the direction of sleeve rotation. As sleeve 52 rotates, detents 6! on washer-like spring 59 are forced out of notches 62. However, each time notches 62 align with and engage detents 6! during rotation of sleeve 52, an audible clicking sound is produced thereby indicating the amount of rotation imparted to sleeve 52. When spring 59 is assembled to post 42, key portions [1 slidably engage in slots II and thereby prevent any rotation of the spring relative to post 42.

When aperture member 58 is elevated suifi- {ciently to disengage vertical keys ID from slots ll, peep 64 can be rotated so that its circumferential edge will lie parallel to the longitudinal axis of the firearm thereby providing a blade type rear sight. In this position, keys 10 will be aligned with slots 41 and counterclockwise rotation of sleeve 52 will lower aperture member 58 in the same manner as when slots 11 were engaged.

Zeroing of the sight in elevation is provided by adjusting screw 5|, the top of which is arranged to seat against the bottom of aperture member 58. If it is desired to change the zero position vertically with respect to the firearm, screw 5| is rotated accordingly within post 42.

I claim:

1. A firearm sight comprising, a base member, means for fixedly mounting said base member to the firearm, a windage slide member movable transversely of said base member, an elevation post pivotally secured to said windage slide, means assumes '7 forilatching 'said post in an upright vertical position relative to said base member, an aperture member slidably engaged with said post during a' predetermined amount of vertical. aperture movement. a ring-like peep sight portion extending upwardly fromwsaid aperture membervand arranged to be disposed with its peripheral edge transverse tothe longitudinal axis of the firearm,

means for actuating said aperture member vertically. up to and beyond the point of disengagement from said post whereby said aperture member is free to rotate relative thereto while still engaged with said actuating means, and means on said post for reengaging said aperture member after 90, rotation thereof whereupon said peep sight is-disposed with its peripheral edge parallel to the longitudinal axis of the firearm thereby forming a blade type sight.

2. A rear sight for a firearm, comprising a base member, means for fixedly mounting said. base member to the firearm, a windage, slide member movable transversely of said base member, an elevation post pivotally secured to said windage slide member and having two pairs of oppositely disposed vertical grooves formed along the outer tion of said aperture member whereby rotation of the former actuates the latter for a predetermined amount of vertical movement, said keys arranged to disengage from one pair of said grooves at the conclusion of said predetermined amount of vertical movement and arranged to re-engage with said other of said pairs of grooves when said aperture member is rotated so as to change said peep sight portion from a position wherein its peripheral edge is disposed transverse of the longitudinal axis of the firearm to a position wherein said peripheral edge is disposed parallel to the longitudinal axis of the firearm or the converse thereof.

3. In a firearm rear sight having an aperture member and means for the vertical adjustment thereof, the combination of, a base member fixedly secured to the firearm, said base member having a transverse counterbored hole therein and a transverse T-slot disposed parallel to the longitudinal axis of said hole so as to intersect there'- with, a windage slide member having a transverse T-shaped portion slidably engaged in said T-slot, means for pivotally mounting the aperture member to said windage slide member, a screw rot'atabl'y carried in said counterbored hole and arranged to engage with a threaded portion on said T-shaped portion of said slide member, a nut rotatably carried in said counterbor'ed hole and having a plurality of spaced lugs thereon in abutting relationship with one end of said screw, a windage knob having an axial stem slidably engageable with said screw whereby rotation of said knob rotates said screw for shifting said windage slide member and therebythe aperture member transversely. with respect to a fixed point on said base member, means for fixedly securing said axial stem to said nut, spring means arranged to 'biassaid knob outwardly and maintain saidsorew in abutting relationshipwith the angular shoulder formed by the counterbored portion. of said hole and thereby prevent backlash between said screw and said threaded portion onsaid windage slide member, and means said base member engageable between saidlugs on said nut to block rotation thereof, all adapted and arranged where-' by movement of said knob against the'bias of said spring means disengages said nut from said blocking means thereby permitting rotation of said screw for effecting windage adjustment to the aperture member.

4. In a rear sight for a firearm, the combination of, a base member fixedly secured to the firearm, said base member having a transverse counterbored hole therethrough and a transverse T- slot disposed parallel to the longitudinal axis'of said hole, said T-slot arranged to eliminate the transverse rear wall of said counterbored hole; a windage slide member having a T-shaped portion extending therefrom and arranged to be slidably engaged in said T-slot, said T-shaped, portion having an arcuate rear face for completin the periphery of said counterbored hole, a threaded portion on said arcuate rear face, a screw rotatably carried in said counterbored hole and arrangedto engage with said-arcuatethreaded portion,means for rotating said screw to actuate said slide transversely with respect to the longitudinal axis of the firearm, and spring means interposed between said base member and said slide member whereby the latter I is constantly biased to the furthest forward position permitted by the clearance existing between said T-shaped portion of said slide member and said T-slot in said fixed base member.

5. In a firearm rear sight, the combination of, a windage slide member having arforwardly pro-,- jecting. substantially rectangular POIlJiDII thG top and front edge of said rectangular portion, term-inating in a common arcuate surface, a hollow elevation post having a pairof bifurcated ears at the lower end thereof arranged to straddle said rectangular portion, means for pivotally securing ranged to increase uniformly in depth from the vertex end to the base end thereof, and spring means biasing said conical head portion on said plunger into the deepest portion of either of said notches whereby one of said ears on said post is forced to abut the respective adjacent side wall of said rectangular portion and thereby, maintain said post against lateral play relative to said windage slide member. I 4

6. 'Ina rear'sight for a firearm, abase member, a windage slide, a hollow elevation post pivotally secured to said windage slide, an aperture having anyexteriorthreaded portion and an upwardly projecting peep sight portionfmeansfor :slidably mounting said apertureion said: elevation post, a hollow sleeve having :a threaded interior portion arranged to surround said aperture and engage said threaded portion thereon whereby rotation of said sleeve adjusts said aperture vertically with respect to. said post, said sleeve having an annular groove within the interior thereof be.

9 low said threaded portion, and a plurality of radially disposed pins slidably mounted in said post, said pins arranged to normally extend sufliciently out of said post to engage in said annular groove for rotatably securing said sleeve to said post.

7. The combination defined in claim 6 wherein said sleeve is provided with a transverse radial hole of lesser diameter than that of said pins, said hole being located in said sleeve in communication with said annular groove therein whereby the rear end of each of said pins is exposed in turn when said sleeve is rotated, said pins being thereby arranged to be forced out of said annular groove for disassemblin said sleeve from said post.

EARLE M. HARVEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 507,278 Latta Oct. 24, 1893 843,145 Gunn Feb. 5, 1907 936,807 Pedersen Oct. 12, 1909 1,113,470 Nelson Oct. 13, 1914 1,344,973 Bader June 29, 1920 1,442,952 Jones Jan. 23, 1923 Redfield Oct. 4, 1927 

